Fitusiran

1 INDICATIONS AND USAGE QFITLIA is indicated for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients aged 12 years and older with hemophilia A or B with or without factor VIII or IX inhibitors. QFITLIA is an antithrombin-directed small interfering ribonucleic acid indicated for routine prophylaxis to prevent or reduce the frequency of bleeding episodes in adult and pediatric patients aged 12 years and older with hemophilia A or B with or without factor VIII or IX inhibitors. ( 1 )

2 DOSAGE AND ADMINISTRATION For subcutaneous use only. Starting dose: 50 mg once every 2 months ( 2.1 ). Monitor AT activity using an FDA-cleared test. Maintain AT activity between 15–35% by adjusting the dose and/or frequency of administration ( 2.2 ). See Full Prescribing Information for important preparation and administration instructions ( 2.4 ). 2.1 Recommended Dosage For subcutaneous use only. Use of QFITLIA is recommended under the supervision of a healthcare professional experienced in the treatment of hemophilia or bleeding disorders. Measure AT activity prior to initiation of QFITLIA. Do not initiate QFITLIA dosing if AT activity is <60%. Monitor AT activity using an FDA-cleared test. Information on FDA-cleared tests for AT activity is available at http://www.fda.gov/CompanionDiagnostics. After QFITLIA is initiated, patients may continue their prior clotting factor concentrates (CFC) or bypassing agent (BPA) prophylaxis for the first 7 days of treatment. Discontinue CFC or BPA prophylaxis no later than 7 days after the initial dose of QFITLIA. The starting dose of QFITLIA is 50 mg once subcutaneously every two months. Adjust the dose and/or dosing interval, if needed, to maintain AT activity between 15–35% [see Boxed Warning , Dosage and Administration (2.2) and Warnings and Precautions (5.1) ] . 2.2 Dosage Modification Measure AT activity using an FDA-cleared test at Weeks 4 (Month 1), 12 (Month 3), 20 (Month 5) and 24 (Month 6) following the starting dose and after any dose modification. If any AT activity is <15%, a dose reduction is required. The lower dose should be initiated 3 months after the prior dose. AT measurements should be restarted after a dose reduction. If AT activity is >35% after 6 months, or if the patient has not achieved satisfactory bleed control, dose escalation should be considered. AT measurements should be restarted after a dose escalation. Refer to Table 1 below for modified dosage based on AT activity levels. Table 1: Dose Modification Based on Antithrombin Activity Levels Last Dosage Administered Antithrombin Activity Level Dose Modification 50 mg every 2 months Less than 15% 20 mg every 2 months 15% to 35% Continue current dosage Greater than 35% after 6 months 50 mg every month 20 mg every 2 months Less than 15% 10 mg every 2 months 15% to 35% Continue current dosage Greater than 35% after 6 months 20 mg every month 10 mg every 2 months Less than 15% Discontinue QFITLIA 15% to 35% Continue current dosage Greater than 35% after 6 months 10 mg every month Once the patient's target dose is identified based on AT activity 15–35%, measure AT activity annually. Additional AT measurements can be considered if bleeding control is not adequate. After cessation of QFITLIA dosing, routine AT monitoring is not needed unless the patient is bleeding and treatment with CFC/BPA is required. Based on data from the clinical studies, a majority of patients have AT activity >60% by 6 months after the last QFITLIA dose, after which standard doses of CFC/BPA may be used. Missed dose If a dose of QFITLIA is missed, administer as soon as possible; thereafter, resume the patient's usual dosing schedule of either once every month or once every two months, as applicable, from the last dose. 2.3 Bleed Management Breakthrough Bleed Management If breakthrough bleeding requiring on-demand treatment with CFC or BPA occurs during the first 7 days after QFITLIA initiation, manage the bleed using the patient's prior dosing regimen of CFC or BPA. If breakthrough bleeding occurs after 7 days from the first QFITLIA dose, bleeds should be managed with a reduced dose and frequency of CFC/BPA to minimize the risk of thrombotic events. Initially, the weight-based dose of a CFC/BPA should be reduced, and the dosing interval doubled compared to the standard dose. This reduced dosing is shown in Table 2. If adequate hemostatic control is not achieved, higher doses may be used based on clinical judgement. Combination use of antifibrinolytics with CFC or BPA has not been studied. Table 2: Breakthrough Bleed Management While Treated with QFITLIA Factor VIII Factor IX (SHL) Factor IX (EHL) aPCC rFVIIa aPCC = activated prothrombin complex concentrate, EHL = extended half-life, rFVIIa = activated recombinant FVII, SHL = standard half-life. Recommended dose 10 IU/kg (maximum: 20 IU/kg) Use clinical judgement for situations requiring higher doses, more frequent administration, or multiple repeat doses. Use standard of care for adjunctive management of bleeding episodes and thrombotic events. 20 IU/kg (maximum: 30 IU/kg) 20 IU/kg (maximum: 30 IU/kg) 30 U/kg (maximum: 50 U/kg) ≤45 μg/kg Repeat dosing Should not repeat in <24 hours Should not repeat in <24 hours Should not repeat in <5–7 days Should not repeat in <24 hours Should not repeat in <2 hours Use of QFITLIA During Surgical Interventions In clinical studies, patients with hemophilia A or B with or without inhibitors have undergone both major (N=60) and minor (N=71) surgical procedures without discontinuing QFITLIA prophylaxis. Utilize bleed management guidelines during the perioperative period for hemostatic management. 2.4 Preparation and Administration Instructions QFITLIA is intended for use under the guidance of a healthcare provider. Provide proper training to patients and/or caregivers on the preparation and administration of QFITLIA prior to use, according to the Instructions for Use (IFU). A patient may self-inject QFITLIA or the patient's caregiver may administer QFITLIA. In pediatric patients 12 to 17 years of age, it is recommended that QFITLIA be administered by or under the supervision of an adult. QFITLIA for subcutaneous administration is a clear, colorless to pale yellow solution. Do not use if the solution is discolored or cloudy, or if it contains visible flakes or particles. Do not use QFITLIA if it has been dropped or damaged. If QFITLIA is stored at room temperature, it is ready for use. If QFITLIA is stored in the refrigerator, remove from the refrigerator and allow QFITLIA to reach room temperature, for at least 30 minutes. Administer QFITLIA by subcutaneous injection in the thigh or abdomen region, except for the 2 inches (5 cm) around the navel. A caregiver can also inject QFITLIA in the outer area of the patient's upper arm. QFITLIA should not be injected into skin that is tender, damaged, bruised, or scarred. Do not inject into a vein. To inject 10 mg or 20 mg of QFITLIA from the single-dose vial, it is recommended to use a sterile 1 mL Luer Lock syringe (polypropylene or polycarbonate), and a sterile 27 gauge ½ inch (13 mm) Luer Lock needle to withdraw and inject QFITLIA solution subcutaneously (see the Instructions for Use). Discard unused product remaining in the prefilled pen or vial.

6 ADVERSE REACTIONS The following clinically significant adverse reactions are described elsewhere in the labeling: Thrombotic Events [see Boxed Warning and Warnings and Precautions (5.1) ] Acute and Recurrent Gallbladder Disease [see Boxed Warning and Warnings and Precautions (5.2) ] Hepatotoxicity [see Warnings and Precautions (5.3) ] Common adverse reactions (incidence >10%) are viral infection, nasopharyngitis, and bacterial infection ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Genzyme Corporation 1-800-745-4447 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The pooled safety population described in the WARNINGS AND PRECAUTIONS reflect exposure to QFITLIA as fixed doses and AT-DR (N=335). The safety of the QFITLIA AT-DR was assessed in 286 adult and pediatric male patients with hemophilia A or B with or without inhibitors [see Clinical Studies (14) ] . Among patients who received the AT-DR, 93% were exposed for 6 months or longer and 83% were exposed for 12 months or longer. The median duration of exposure across the studies was 674 days (with a maximum of 896 days). Serious adverse reactions occurred in 4/286 (1.4%) patients who received the AT-DR, two of whom had serious adverse reactions of cholecystitis. Permanent discontinuation of QFITLIA due to an adverse reaction occurred in 4/286 (1.4%) patients receiving the AT-DR and included liver injury, post-operative deep vein thrombosis, cerebral infarction and pruritus. Dosage interruptions of QFITLIA due to an adverse reaction occurred in 2/286 (0.7%) patients receiving the AT-DR and included increased serum transaminases. The most common adverse reactions (≥10%) reported in patients treated with the AT-DR were viral infection, nasopharyngitis, and bacterial infection. Table 3: Adverse Reactions Reported in ≥5% of Patients from Pooled Clinical Studies with QFITLIA AT-DR Adverse Reaction Number of Patients (%) N=286 Viral infection Includes similar terms. 29 Nasopharyngitis 26 Bacterial infection 11 Hepatic Injury Hepatic injury includes: alanine aminotransferase increased, aspartate aminotransferase increased, liver injury. 8 Arthralgia 8 Prothrombin fragment 1.2 increased 7 Injection site reaction injection site reactions: includes injection site bruising, injection site erythema, injection site pain, injection site hematoma, injection site atrophy, injection site hemorrhage, injection site discomfort, injection site swelling, injection site discoloration, injection site pruritus, injection site induration, injection site nodule, injection site mass, injection site vesicles, injection site deformation, injection site rash, injection site joint pain and application site erythema. 6 Headache 5 Cough 5 Clinically relevant adverse reactions in less than 5% of patients include: Dyspepsia Abdominal pain

12.3 Pharmacokinetics The pharmacokinetic (PK) properties of fitusiran were evaluated following administration of QFITLIA in patients with hemophilia A or B, with or without inhibitors as summarized in Table 4. QFITLIA PD is driven by liver PK rather than plasma PK. The QFITLIA dosing strategy is based on maintaining plasma AT activity levels between 15–35% with 10, 20 or 50 mg dosing every month or every two months. Table 4: Pharmacokinetic Parameters of QFITLIA PK Parameters Unless otherwise indicated, the PK parameters in this table are from Study LTE15174. All PK parameters are estimated using non-compartmental analysis and are presented as Mean (SD) [CV%], except for t max which is presented as median (range) QFITLIA 20 mg QFITLIA 50 mg AUC = area under the plasma concentration-time curve extrapolated to infinity; CL/F = apparent clearance; C max = maximum plasma concentration; CV = coefficient of variation; PK = pharmacokinetic(s); SD = standard deviation; t 1/2 = terminal elimination half-life; t max = time to maximum concentration; Vss/F = apparent volume of distribution General Information Steady State Exposure: C max (ng/mL) 34.4 (10.1) [29%] 84.1 (58.7) [70%] AUC (ng ∙ h/mL) 491 (83.8) [17%] 1290 (377) [29%] Dose Proportionality QFITLIA exhibited a dose proportional increase in plasma exposure after SC administration. Accumulation Study TDR14767 (ALN-AT3SC-001) No accumulation of QFITLIA was observed following multiple once monthly dosing. Absorption t max (h) 2.88 (0.5 – 4.33) 3.78 (0.42 – 11.9) Distribution QFITLIA distributes primarily to the liver after subcutaneous injection. Vss/F 431 (135) [31%] 570 (713) [125%] Protein Binding In vitro data 96.6% at clinically relevant exposure (0.5 microgram/ml) Elimination t 1/2 (h) 5.57 (2.36) [42%] 7.98 (4.74) [59%] CL/F 41.9 (8.39) [20%] 50.8 (71.1) [140%] Metabolism Primary Pathway QFITLIA is metabolized by endo- and exo-nucleases to oligonucleotides of varying lengths, which are further metabolized to oligonucleotides of even shorter lengths. QFITLIA is not a substrate for CYP450 or transporters. Main Metabolite AS(N-1)3' Excretion Primary Pathway Not evaluated 14.6% (mean) of the administered 50 mg dose of QFITLIA is recovered unchanged in 0–24 hour urine Specific Populations QFITLIA has only been studied in male patients. The pharmacokinetics of fitusiran is not influenced by race. QFITLIA has not been studied in children <12 years old. No clinical study to evaluate the effect of hepatic impairment or renal impairment on the pharmacokinetics of QFITLIA was conducted. In the pivotal studies, 12 patients had mild renal impairment (eGFR ≥60 to <90 mL/min/1.73 m 2 ) and 1 patient had moderate renal impairment (eGFR 30 mL/min/1.73 m 2 to <60 mL/min/1.73 m 2 ). Population PK analysis indicated no impact of renal impairment on the exposure (C max and AUC) of QFITLIA in patients with mild renal impairment. Drug Interaction Studies Clinical Studies No clinical drug-drug interaction studies have been conducted to evaluate the potential of QFITLIA to interact with other co-administered drugs which are either substrates, inhibitors or inducers of CYP isozymes, or are substrates or inhibitors of drug transporters. In Vitro Studies Results from in vitro studies evaluating the potential of co-administered drugs to increase the PK exposure of QFITLIA, and the potential of QFITLIA to increase the PK exposure of co-administered drugs, indicate that CYP- or transporter-mediated interactions between QFITLIA and co-administered drugs are unlikely at clinically relevant concentrations.